A computer network is a collection of interconnected computing devices that exchange data and share resources. In a packet-based network, such as the Internet, the computing devices communicate data by dividing the data into small blocks called packets. The packets are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form. Dividing the data into packets enables the source device to resend only those individual packets that may be lost during transmission.
To route the packets through the computer network, each network device may be assigned an address that uniquely identifies each of the requesting network devices. Each packet may then include a source address uniquely identifying the network device that originated the packet and a destination address uniquely identifying the network device to which the packet is destined. Intermediate devices, referred to as routers, may route the packets to the destination device based on the destination address included within the packet.
Typically, each network device, upon attempting to access the network, may request configuration information that includes an Internet Protocol (IP) address in accordance with a Dynamic Host Configuration Protocol (DHCP). For example, a subscriber device (e.g., a cable modem, a digital television setup box, a Digital Subscriber Line (DSL) modem) may request a layer three IP network address by issuing a DHCP request to a DHCP server. Often, access routers located near the requesting subscribe device implement what is referred to as a “local” DCHP server to service these DHCP requests. A DHCP server implemented by an access router is considered local in that it is positioned within the same sub-network as that of the requesting subscriber device. Because these DHCP servers are local, the servers implemented by the access routers may more quickly respond to the DHCP server requests issued by the client network devices.
While local DHCP servers usually improve response times with respect to DHCP requests, these local DHCP servers may be more difficult to administer and waste address resources. For example, each of these local DHCP servers typically needs to be configured to allocate IP addresses from a different portion of an IP address space assigned to the enterprise. Misconfiguring any of the DHCP servers such that two or more of the servers have portions that overlap may cause significant network conflicts as two different subscriber devices may be assigned the same IP address, thereby preventing routers from being able to individually route traffic to one or the other of these devices. In addition, any given local DHCP server typically only utilizes a small amount of its assigned portion of the IP address space at any one time. This wastes address resources in that the unused addresses in the assigned portion could be used by another local DHCP server.
To avoid the administrative difficulty and address waste associated with local DHCP servers, a central DHCP server is often employed to centrally allocate addresses from the IP address space. Rather than divide the IP address space into portions, the central DHCP server receives the DHCP requests from the routers, reserves an address from the centrally maintained IP address space, and forwards the reserved address to the requesting subscriber devices effectively assigning the reserved address to these subscriber devices remotely. While more easy to administer than local DHCP servers implemented by routers, the central DHCP server is often implemented as a stand-alone device, which increases costs considering that another device in addition to the routers need be purchased to implement the central DHCP server. Moreover, the central DHCP server typically cannot respond to DHCP requests as quickly as the local DHCP servers due to its central, rather than local, location.